1. Field of the Invention
The present invention relates to a method, system, and an article of manufacture for transferring structured data between different data stores.
2. Description of the Related Art
A database management system, such as a relational database management system, may store data in tables comprised of rows and columns. The types of data in the columns of a table are defined when the table is created. In some database management systems the types of data may be limited to instances of a base data type, such as instances of an integer data type, a real data type, a string data type, a character data type etc.
In other database management systems, values within the columns of a table are not limited to instances of a base data type but can be instances of user-defined structured data types. A structured data type is a data type made up of a collection of one or more attributes, where each attribute may be of a base data type or a structured data type. A type name identifies a structured data type. Subtypes may extend an existing structured data type reusing all of the attributes of the structured data type and contain additional attributes specific to the subtype. For example, a structured data type with the type name Person might contain attributes for Name, Age, and Address. A subtype of Person might be named Employee, where the subtype Employee contains the attributes Name, Age, and Address and in addition contains attributes for SerialNumber, Salary, and BusinessUnit. An instance of a structured data type includes an identifier, where the identifier identifies the structured data type in the database management system where the structured data type was created.
If a column is of a particular structured data type, the values within the column can be instances of either the structured data type or of any subtype of the structured data type. Further details of structured data types in database management systems are described in the publication entitled “IBM DB2 Universal Database: Application Development Guide, Version 7” (copyright, IBM 2001), which publication is incorporated herein by reference in its entirety.
Database management systems may transfer data from a source database to a target database. In prior art database management systems, when values within a column are instances of a well-known base data type, the target database can interpret the transferred data. However, if the values within a column are instances of user-defined structured data types, in prior art database management systems the target database cannot interpret the transferred data.
Hence, there is a need in the art to provide techniques for transferring structured data between database management systems.